Determining Electron Transfer Kinetics at Porous Electrodes

Abstract

Newcastle University ePrints -eprint.ncl.ac.uk Friedl J, Stimming U. Determining Electron Transfer Kinetics at Porous Electrodes. Electrochimica Acta 2017, 227, 235-245.Abstract:Porous carbon materials are of tremendous importance for electrochemical energy storage. Their low cost, wide potential window and high surface area make them ideal electrodes for many applications.The activity of the electrode towards a certain reaction is given by both the available wetted surface area and the electron transfer constant k 0 . The present study investigates which electrochemical methods are suitable to determine k 0 on porous carbon electrodes. For this purpose, we investigate the ferric/ferrous redox couple on a porous carbon nanotube electrode as model system. We show that results from cyclic voltammetry (CV) can yield an apparent catalytic effect and elucidate its origin.Chronoamperometry and electrochemical impedance spectroscopy are shown to produce consistent values for the exchange current density I 0 , which can then be normalized to k 0 . Limitations of both

The Vanadium Redox Reactions – Electrocatalysis versus Non‐Electrocatalysis

“…So, an important task is to analyse the reaction rate of the vanadium redox reactions, both V(II)/V(III) and V(IV)/V(V) as a function of various kinds of surface treatment of carbon. Analysing the literature about previous results yields an obscure picture . The rate constants of charge transfer, k 0 , of Eq.…”

“…It is important to analyse the experimental procedure of pre‐treating the electrode material, the surface condition of the electrode regarding porosity and the experimental techniques used to analyse the data. Such an analysis was done in . It turns out that the porosity of the carbon surface and the way the reaction rate was evaluated have a significant impact on the value of the determined rate constant.…”

“…Systematic experiments to evaluate the effect of surface treatment on the kinetics of the Fe(II)/Fe(III), the V(II)/V(III) and the V(IV)/V(V) reactions were performed using Eq. 2 to determine the rate constants . In addition, it was evaluated which experimental techniques are suitable (or not) to determine reaction rates on porous surfaces …”

A Simple Procedure to Fabricate Paper Biosensor and Its Applicability—NADH/NAD+ Redox System

“…These low values indicate very slow kinetics of the NAD + reduction reaction on a glassy carbon electrode and reflect the over potential necessary for the redox reaction which is related to both redox kinetics and mass transport. One strategy employed to overcome these difficulties (fouling and overvoltage and side reactions) was the use of mediator-modified electrodes, where the mediators are used to shuttle electrons from NADH to the electrode surface and allow electron transport between them [5,[9][10][11][12][13][14][15][16]. Some mediators (electrocatalysts) were immobilized on the electrode surface by covalent attachment, electrochemical polymerization, incorporation in carbon paste, adsorption, self-assembly and via entrapment in polymeric matrices [4,[17][18][19].…”

“…Some mediators (electrocatalysts) were immobilized on the electrode surface by covalent attachment, electrochemical polymerization, incorporation in carbon paste, adsorption, self-assembly and via entrapment in polymeric matrices [4,[17][18][19]. Another strategy is modification of the electrode surface with a polymeric substance, using electrodes modified with carbon nanotubes, nanofibers or using enzymatic methods that follow bioelectrocatalytic reaction [2,4,13,15,16,[20][21][22][23]. Investigation in this area usually explores the mediator use or the surface modification to improve the electrochemical detection [15,21,[24][25][26][27][28].…”